With constant practice of oil and gas development, early conventional oil and gas reservoir development is now drawing to a close. Unconventional oil and gas reservoirs and complex oil and gas reservoirs, from shallow to deep ones, are now being developed. Geological-oriented construction is becoming increasingly common in these unconventional oil and gas reservoirs and complex oil and gas reservoirs. As modern electronic measurement technology continuously develops, an imaging measurement while drilling (MWD) apparatus can be used to measure engineering parameters such as well deviation and azimuth at a drill bit, and geometrical parameters such as resistivity, gamma, sound waves, and nuclear magnetism in a drilling procedure in real time, and realize imaging of the resistivity, gamma, sound waves, nuclear magnetism, etc.
Quite a large amount of imaging measurement data can be obtained in a drilling procedure. Taking MWD sound waves as an example, at least 250 Mbyte of data are required to enable complete storage of effective information. If other parameters are also measured, rather a huge amount of data will be necessary. However, a mud pulse performing real-time transmission has a transmission speed of smaller than 10 bit/s at the time of drilling. It is impossible for such a transmission speed to complete transmission of these data in the drilling procedure. Therefore, typically, these data are temporarily stored in an MWD apparatus until the drilling is completed and the MWD apparatus is pulled back to the ground, and then downloaded to a ground computer through cable transmission.
In order to complete the above task, it is necessary to specially provide a data download interface on a surface of the MWD apparatus, which is sealed at a high pressure and high temperature in a downhole through a cover. During data transmission, the cover is open to connect the MWD apparatus to a cable and a computer. Such a special design of the data download interface not only is inconvenient, but also increases costs.
On the other hand, two drilling modes are often used in directional drilling. In one of the two drilling modes, a ground power device does not drive a drill shaft to rotate, and only mud circulation drives the drill bit to drill by means of a screw. Such a drilling mode is also termed slide drilling, during which, a region of the MWD apparatus above the screw does not rotate. The other of the two drilling modes is compound drilling. In this operation mode, the ground power device drives the drill shaft to rotate, and also drives all drilling tools in downhole to rotate. Meanwhile, mud circulation drives the drill bit drill by means of the screw. In this case, the region of the MWD apparatus above the screw rotates. However, it is impossible to enable imaging in both of the above cases in the prior art.